Electron–acoustic-phonon interaction in core/shell Ge/Si and Si/Ge nanowires

Abstract

General expressions for the electron-and hole-acoustic-phonon deformation potential Hamiltonians (HE−DP ) are derived for the case of Ge/Si and Si/Ge core/shell nanowire structures (NWs) with circular cross section. Based on the short-range elastic continuum approach and on derived analytical results, the spatial confinement effects on the phonon displacement vector, the phonon dispersion relation and the electron-and hole-phonon scattering amplitudes are analyzed. It is shown that the acoustic displacement vector, phonon frequencies and HE−DP present mixed torsional, axial, and radial components depending on the angular momentum quantum number and phonon wavevector under consideration. The treatment shows that bulk group velocities of the constituent materials are renormalized due to the spatial confinement and intrinsic strain at the interface. The role of insulating shell on the phonon dispersion and electron-phonon coupling in Ge/Si and Si/Ge NWs are discussed.

Localized Phonon Transport Study of GaN/SiO2 Core/shell Nanowires under Thermal-Stress Coupling

“…The carrier transport characteristics of core/shell NW are influenced not only by the modulation of core and shell materials but also by strain effects. In the practical application of wurtzite core/shell nanocrystal devices, nanocrystals are often subjected to external loads . The band bending effect of the charge density in the core/shell and multishell semiconductor NW strongly depends on strain relaxation-1.…”

“…In the practical application of wurtzite core/shell nanocrystal devices, nanocrystals are often subjected to external loads. 14 The band bending effect of the charge density in the core/shell and multishell semiconductor NW strongly depends on strain relaxation 15 -1 16 . Strain effects not only significantly influence semiconductor electronic properties but also alter the material's phonon characteristics, reconstructing phonon dispersion relations, thereby affecting the material's thermal conductivity.…”